Strange behavior on port 50000 for Owin self hosting.... about aspnetkatana

[Tratcher]

What's the full error message?

[harperjohn]

[harperjohn]

@Tratcher Did the "owin" example work without error for you?

[Tratcher]

Ah, I do see the same error. This post might explain why: https://stackoverflow.com/questions/54010365/how-to-see-what-is-reserving-ephemeral-port-ranges-on-windows

[harperjohn]

Interesting @Tratcher !

PS C:\Users\john> netsh int ip show excludedportrange protocol=tcp

Protocol tcp Port Exclusion Ranges

Start Port End Port

---

 50000       50059     *

• • Administered port exclusions.

[harperjohn]

Ok... So something is reserving those ports...

But now I am very very curious why the asp.net either does not "see" or does not "care" or just overrides the reservation for some reason... (and it just just asp.net... the Hugo static site generator has a built in web server, and it gladly uses 50000)

[Tratcher]

In AspNetCore you're using the Kestrel server by default which runs in user mode with direct Sockets. In Owin self-host you're using HttpListener -> Http.Sys which runs in kernel mode. I don't know why the Http.Sys stack honors those reservations when Sockets don't, but that would explain why other apps your using don't care either.

[Tratcher]

Closing as answered/external.